• Make the Dough (Morning): In a large mixing bowl, combine the yeast and warm water. Stir until the yeast dissolves.
• (Add Sweeteners and Liquids): Next, stir in the honey, yogurt/sour cream, one whole egg, and one egg white (reserve one yolk for brushing).
• Incorporate Fat: Whisk in the melted butter until fully combined with the wet ingredients.
• Mix in Dry Ingredients: Gradually add the flour and salt to the wet ingredients. Use a spatula or your hands to knead the dough until it becomes a soft, semi-sticky ball. Avoid over-kneading.
• Dough Rise: Cover the bowl with plastic wrap or a clean kitchen towel and let the dough rise in a warm place for 2-3 hours, or until doubled in size.
• Preheat the Oven: Since you planned ahead like a champ, your yeast dough should be beautifully risen by now! While you prepare the filling, preheat your oven to 400°F (200°C) so it's nice and hot for even baking later.
• Sauté the Vegetables: Heat olive oil in a large pan over medium heat. Start by adding the chopped onions and cook until softened, about 1 minute. This step builds the base flavor for the filling.
• Introduce the Mushrooms: Now, add the sliced yellow oyster mushrooms and cook for just 2 minutes, stirring occasionally. We want to retain their delightful texture, so a quick sear is perfect.
• Season and Spice Up: Once the onions soften and the mushrooms get a nice sear, it's time for the flavor fiesta! Stir in the turmeric powder, sumac, salt, and pepper. These spices will add warmth and depth to the filling.
• Incorporate Remaining Veggies and Broth: Toss in the chopped carrots, bell peppers, and snap peas. Cook for another minute, letting them mingle with the seasoned base. Now, add the red lentils and sun-dried tomatoes for a touch of heartiness and tang. Finally, pour in the chicken broth. Bring the mixture to a boil, then reduce heat, cover the pan, and simmer for 10 minutes. This allows the lentils to become tender and the flavors to meld harmoniously.
• Finishing Touches for the Filling: Once simmered, remove the pan from heat and stir in the barberries and chopped parsley. These add pops of color and brightness to your filling. Let the filling cool slightly while you assemble the piroshki. This ensures the dough doesn't cook unevenly from hot filling.
• Assemble and Bake: Divide your risen dough into 8 equal pieces. On a lightly floured surface, flatten each piece into a circle. Spoon a generous amount of the cooled filling onto one half of the dough circle. Fold the dough over the filling, forming a crescent shape. Pinch the edges to seal. Repeat with remaining dough and filling.
• Brush and Bake: Now that your piroshki are assembled, brush the tops with beaten egg yolk. This adds a beautiful golden sheen during baking. If you like an extra touch, sprinkle them with poppy seeds. Finally, bake the piroshki in your preheated oven at 400°F (200°C) for 20 minutes, or until golden brown.
• Enjoy!: Let the piroshki cool slightly before serving. Enjoy them plain or with your favorite dipping sauce.

I ended up making 6 piroshki from this recipe, but the filling was so good, I had some leftover! Don't worry, it didn't go to waste. I enjoyed the extra filling in a refreshing lettuce wrap. This recipe is easily scalable. Feel free to use half the dough and filling for a smaller batch, and freeze the remaining dough for next time. Just remember to thaw the dough at room temperature for 5 hours before baking for perfect results.